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I wonder if you could use a similar sort of device with weather balloons to harvest water from clouds.

I could totally see a Project Loon style craft which automatically surfs the crosswinds, going up above the clouds to radiate heat to the open sky at night, and descending to condense water.

Would dry regions that need water have enough cloud coverage for that to be viable?

My guess is that any place with sufficient cloud coverage is already getting enough rain water to satisfy their needs.

I think there are parts of coastal California where there are clouds more of the year than rainfall. I'd also suspect if you just raised them up with balloons to cool them off and then brought them down where it's warmer, you could condense evaporation from the ocean, without spending energy directly on cooling.

You’d have to raise them up pretty high to get them colder than the dew point.

The energy it’d take to raise and lower the material would make it cost prohibitive.

I considered that the balloons would be a balancing force but don’t forget the rope length changes as the balloons go up and down. That changing length shifts the weight around. You can’t be balance against it.

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